Telescoping-Tube System For Crew Transfer

ABSTRACT

A system and method for transferring crew members between a first platform and a second platform, at least one of which platforms is subject to movement, is disclosed. The system includes a telescoping-tube assembly having at least three nestable tubes. The tubes are capable of being extended and retracted as well as being selectively locked to ensure that a crew member traversing the tube assembly always travels along a rigid connection between adjacent tubes. A sensor system is used to sense the location and direction of movement of a crew member within the tubes.

FIELD OF THE INVENTION

The present invention relates generally to the field of maritime equipment and more particularly to a telescoping-tube system for crew transfer between a vessel and a stationary platform.

BACKGROUND OF THE INVENTION

The use of large marine-based oil rigs has increased the need for a safe, efficient and cost effective method for the transfer of crew members between support vessels and stationary oil rig platforms. Currently, crew transfer is usually accomplished using helicopters, which is costly, subject to weather restrictions, subject to airspace restrictions and capable of transporting only a limited number of personnel per flight. Location of oil rig platforms at extended distances from shore based facilities adds to the disadvantages of this method.

In addition to helicopters, cranes operating on oil rig platforms are often used to lift a basket containing personnel to transfer the personnel between a support vessel and the oil rig platform. Cranes require crane operators and handlers stationed to open and lock the baskets. And there is operational risk to the crew being transferred as well as the handlers. Also, only a limited number of personnel can be transferred at a time, such that the process is both time consuming and inefficient. Crew transfer operations at present are labor intensive and present certain risks, especially if performed in higher sea states.

The prior art related to crew transfer apparatus includes a transfer system developed by Lockheed Martin. The apparatus, named “Viking,” includes a flexible ladder apparatus (Selstair®) that is permanently mounted on an oil rig as well as a walkway, identified as a CEWay™, for bridging the gap between the support vessel and the flexible ladder. The CEWay™ includes a fixed-length walkway having an end mounted on a sled that runs on tracks mounted on the support vessel. This system utilizes the flexible ladder for vertical crew transfer and the walkway for horizontal or near horizontal crew transfer.

Additional approaches for connecting a static structure to a dynamic structure, as disclosed in the following references, have various drawbacks.

Publ. U.S. Pat. Appl. No. 2006/0191457 A1 discloses a telescoping gangway that includes a pair of relatively flat walkway sections supported by a hydraulic cylinder. The gangway provides no personnel protection from weather conditions and does not accommodate relative motion between the boat, on which the device is mounted, and a stationary structure. Furthermore, there is no provision for efficient storage of the gangway when not in use.

U.S. Pat. No. 6,131,224 discloses a flat rigid connecting bridge and a pair of multi-directional trunnion and roller assemblies for accommodating relative motion between a static and a dynamic structure. A trunnion and roller assembly is attached to the static structure and to the dynamic structure and the trunnion and roller assemblies support the connecting bridge. This system does not protect the crew from weather conditions. Furthermore, storage is not provided for the device when it's idle.

U.S. Pat. No. 2,641,785 discloses a rigid walkway that is supported by a crane. A first end of the walkway is connected to a dock by a pivoting hinge connection and the second end of the walkway connected to a boat by a ball joint. The rigid configuration of the walkway prevents compact storage when the device is not in use.

U.S. Pat. No. 4,333,196 discloses a rigid walkway for coupling a stationary platform to a vessel. The first end of the walkway is pivotably coupled to the stationary platform. The second end of the walkway rests on the vessel. The rigid configuration of the walkway prevents compact storage when the device is not in use.

The prior art devices are not able to provide safe operation in higher sea states. This results in relatively high costs and potential operational interruptions and reliability problems. Nor do the prior art devices provide for compact storage of the devices on a vessel when the devices are not in use. Simply put, the prior art does not provide a safe and effective solution for transferring crew members between a vessel and a stationary platform.

SUMMARY OF THE INVENTION

The present invention provides a crew-transfer system for transferring crew between a first platform, such as a floating vessel, and second platform, such as oil rig, that avoids at least some of the disadvantages of the prior art.

In the illustrative embodiment, the system comprises: a telescoping-tube assembly comprising three nestable/extendable tubes, a first coupling that movably couples a proximal end of the telescoping-tube assembly to a moving platform (e.g., a floating vessel, etc) and a second coupling that reversibly and movably couples the distal end of the telescoping-tube assembly to a stationary platform (e.g., oil rig, etc.).

The tubes are of sufficient internal diameter to accommodate a crew member who must transit between the two platforms. A ladder is advantageously disposed in each tube to enable a crew member to traverse the tubes, especially when one platform is at a different height than the other. In the illustrative embodiment, linear actuators are used to extend/retract the three tubes.

The largest (i.e., outermost) of the tubes is operatively coupled to a lift mechanism that raises and lowers the distal end of the telescoping-tube assembly. Once raised, the tubes of the telescoping-tube assembly are deployed (extended) via the linear actuators.

After the tubes are raised and extended, the smallest (i.e., innermost) tube is reversibly coupled to the stationary platform by the second coupling. In the illustrative embodiment, the second coupling comprises a male portion that depends from the end of the innermost tube and a female portion that is disposed on the stationary platform. The second coupling is capable of temporarily locking, to ensure that the distal end of the telescoping-tube assembly remains coupled to the stationary platform until transfer operations are complete.

In the illustrative embodiment, the linear actuators, in conjunction with a control system, selectively lock two of the extended tubes of the telescoping-tube assembly. In particular, the linear actuators are controlled to lock two adjacent tubes while leaving the remaining tube free to move relative to an adjacent tube. The locking functionality operates in conjunction with a motion-sensing system, which senses the presence of a crew member in a particular tube and is used to determine the crew member's direction of travel. Based on information from the motion-sensing system, both the tube in which the crew member is then positioned and the adjacent telescoping tube along the crew member's direction of travel are locked. This ensures that the crew member travels along a rigid connection between adjacent telescoping tubes. The system also ensures that the third tube (in the illustrative three-tube system) is free to move relative to an adjacent tube. This enables the telescoping-tube assembly to move in the axial direction (i.e., along its length) to accommodate relative translational movement between the first and second platform as can be caused by wave motion.

In preferred embodiments, the first and second couplings have a sufficient number of degrees of freedom to accommodate rotational motions of one or both of the platforms. Typically, only one of the platforms (e.g., a floating vessel, etc.) is subject to such motion, which is a natural consequence of wave motion. Specifically, the platform(s) will experience rotational motions in the pitch, roll and yaw directions. Providing first and second couplings that accommodate these rotational motions serves to significantly mitigate the stresses that would otherwise be induced in the telescoping-tube assembly when in use.

In the illustrative embodiment, the first coupling and the second coupling are each implemented as a ball and socket joint. The ball and socket joint will provide at least three degrees of freedom (of motion). In the absence of additional stabilization, implementing both the first and second coupling as a ball and socket joint would render the telescoping-tube assembly unstable. In particular, the telescoping tube assembly would be able to “roll” (i.e., rotate about its longitudinal axis). As a consequence, one coupling (preferably the second coupling) is limited to two degrees of freedom (pitch and yaw). This can be accomplished in various ways, such as by modifying the ball and socket joint, or using cables that prevent the telescoping tube assembly from rolling, or via other features that, by virtue of their attachment to the telescoping-tube assembly, limit the movement thereof.

As previously noted, in additional to rotational motions, waves will cause a floating vessel to move towards or away from the stationary platform. In other words, wave motion will result in translational movement of a floating vessel. This movement is accommodated, as previously noted, by ensuring that one of tubes of the telescoping-tube assembly is free to slide (i.e., extend or retract) with respect to one of the other tubes of the assembly.

A set of cables optionally connects the largest tube to the deck of the vessel. Additional cables optionally connect the end of the extended telescoping-tube assembly to the stationary platform. As previously discussed, depending upon how the first and second couplings are implemented, these cables might be required to prevent “roll” of the telescoping-tube assembly. In some embodiments, a cable connects the support vessel and the stationary platform. This cable can be used to limit the relative translational movement of the floating vessel and the stationary platform.

In some embodiments, the present invention provides a crew-transfer system comprising:

a telescoping-tube assembly, a first coupling that movably couples a proximal end of the telescoping-tube assembly to a first platform, and a second coupling that movably and reversibly couples a distal end of the telescoping-tube assembly to a second platform, wherein the telescoping-tube assembly comprises:

-   -   (a) at least three tubes; and     -   (b) a first mechanism that selectively locks two adjacent tubes         of the at least three tubes, wherein the tubes are selected for         locking based on:         -   (i) a location of a user within the telescoping-tube             assembly; and         -   (ii) a direction of travel of the user therethrough, wherein             the locked tubes include the tube in which the user resides             and the tube to which the user is next heading.

In some additional embodiments, the present invention provides a crew-transfer system comprising:

a telescoping-tube assembly, a first coupling that couples a proximal end of the telescoping-tube assembly to a first platform that, in use, is subjected to forces that cause the first platform to move in at least three different directions, and a second coupling that reversibly couples a distal end of the telescoping-tube assembly to a second platform, and wherein the telescoping-tube assembly comprises:

-   -   (a) at least three tubes that allow ingress and egress for a         user;     -   (b) a motion-sensing system for sensing the presence and         direction of movement of the user through the tubes; and     -   (c) a first mechanism for extending and retracting the at least         three tubes;

and wherein the first coupling is structured to accommodate the movement of the first platform by providing three degrees of freedom of movement between the telescoping-tube assembly and the first platform.

In yet some further embodiments, the present invention provides a crew transfer system comprising:

a telescoping-tube assembly, a first coupling that couples a proximal end of the telescoping-tube assembly to a first platform, and a second coupling that reversibly couples a distal end of the telescoping-tube assembly to a second platform, wherein the telescoping-tube assembly comprises:

-   -   (A) at least three tubes that allow ingress and egress for a         user;     -   (B) a motion-sensing system for sensing the presence and         direction of movement of the user through the tubes; and     -   (C) one or more mechanisms that:         -   (i) extend and retracting the at least three tubes;         -   (ii) selectively locks two adjacent tubes of the at least             three tubes, wherein the tubes are selected for locking             based on:             -   (a) a location of a user within the telescoping-tube                 assembly; and             -   (b) a direction of travel of the user therethrough,                 wherein the locked tubes include the tube in which the                 user resides and the tube to which the user is next                 heading.

In still further embodiments, the present invention provides a crew-transfer system that couples to a first platform and reversibly couples to a second platform, wherein the crew-transfer system comprises:

a telescoping-tube assembly, the telescoping-tube assembly comprising:

-   -   (A) a first tube, second tube, and third tube that are suitably         dimensioned to permit passage therethrough by a human user;     -   (B) a motion-sensing system for sensing the presence of the user         and a direction of movement of the user through the tubes; and     -   (C) a plurality of linear actuators selected from the group         consisting of mechanically-coupled rodless cylinders or         magnetically-coupled rodless cylinders, wherein the linear         actuators are disposed between:         -   (i) an inner surface of the first tube and an outer surface             of the second tube; and (ii) an inner surface of the second             tube and an outer surface of the third tube.

In a further aspect of the invention, the present invention provides a method for transferring crew members comprising:

-   -   extending, from a first platform to a second platform, a         plurality of telescoping tubes; temporarily coupling, to the         second platform, an end of a distal-most tube of the telescoping         tubes;     -   sensing a presence of a user moving within the telescoping         tubes;     -   determining a direction of travel of the user; and     -   locking both the telescoping tube in which the user resides at         the time of sensing and an adjacent telescoping tube in the         direction in which the user is traveling.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A depicts a simplified overall schematic side view of a crew transfer system in accordance with the illustrative embodiment of the present invention. The system is depicted mounted on a vessel in a quiescent state ready for deployment.

FIG. 1B depicts the system of FIG. 1A during the process of deployment.

FIG. 1C depicts the system of FIGS. 1A and 1B after the deployment of the system has been completed with the system ready for crew transfer.

FIG. 2 depicts an end view the system of FIG. 1C.

FIG. 3 depicts a view of the system taken along the line 3-3 of FIG. 1C.

FIG. 4 depicts a cross-sectional view of the telescoping-tube assembly taken along the line 4-4 of FIG. 2 and also depicts a simplified schematic of a control system.

FIG. 5 depicts the first coupling, which couples the telescoping-tube assembly to a first platform, such as a vessel.

FIG. 6 depicts the second coupling, which couples the telescoping-tube assembly to a second platform, such as an oil rig.

FIG. 7 is a view taken along the line 7-7 of FIG. 6.

FIG. 8 depicts a simplified cross-sectional view taken along the line 8-8 of FIG. 6.

FIG. 9 depicts a simplified cross-sectional view taken along the line 9-9 of FIG. 6.

FIG. 10 depicts a simplified cross-sectional view of a rodless pneumatic linear actuator.

FIG. 11 depicts a simplified cross-sectional view of a magneto-rheological (MR) linear actuator.

FIG. 12 depicts a simplified cross-sectional view of a magnetically coupled rodless linear actuator.

FIG. 13 depicts a simplified elevation view of an electro-mechanical ball screw linear actuator.

FIG. 14 depicts the manner in which the telescoping-tube assembly adapts to changes in the relative position of the first platform and the second platform.

FIG. 15 is a simplified flow diagram depicting a process in accordance with the illustrative embodiment of the present invention.

DETAILED DESCRIPTION

FIGS. 1A through 1C provide an overview of the structure and operation of telescoping-tube system for crew transfer 100 in accordance with the illustrative embodiment of the present invention. The system 100 creates a temporary connection that enables safe and efficient crew transfer between a first platform and a second platform.

The system is advantageously used in applications in which at least one of the platforms is subject to forces that cause it to move, such as when one of the platforms is floating and therefore subject to wave motion. One particularly useful application—and the context for the illustrative embodiment—is the creation of a temporary connection for crew transfer between a floating vessel and a stationary platform such as oil rig. Of course, crew transfer system 100 can also be used for crew transfer operations when both platforms are moving or when neither platform is moving. But in the latter case, much of the capability that is provided by system 100 would not be required.

FIG. 1A depicts system 100 in a quiescent state, before deployment of system 100 and showing only a single tension line 106 connecting vessel 102 and stationary platform 104. FIG. 1B depicts system 100 in an actuated state wherein telescoping-tube assembly 108 is partially extended but before the end of telescoping-tube assembly 108 has made contact with stationary platform 104. FIG. 1C depicts full connection between vessel 102 and stationary platform 104 for crew transfer.

Referring now to FIGS. 1A-1C and FIG. 2, the salient features of system 100 include: telescoping-tube assembly 108, first coupling 112, lift mechanism 114, and male portion 124 and female portion 180 of a second coupling.

Telescoping-tube assembly 108, which has posterior end 109 and anterior end 110, comprises three tubes 118, 120, and 122, wherein tube 118 has the largest diameter and tube 122 has the smallest diameter. The tubes are suitably dimensioned to enable personnel to move freely therein. The tubes are capable of nesting (as shown in FIG. 1A) and extending (FIG. 1C shows the tubes fully extended). As depicted in FIG. 2, tube 118 includes ports 208 and 210 that enable crew members to enter or exit telescoping-tube assembly 108 for transit from or to support vessel 102. Port 212 of tube 122 permits crew members to exit or enter telescoping-tube assembly 108 for transit to or from stationary platform 104. The telescoping tubes are preferably made from a material that is relatively light in weight, relatively stiff, and highly resistant to corrosion; for example, fiberglass.

Telescoping-tube assembly 108 is movably coupled to vessel 102 proximal to posterior end 109 via first coupling 112. When in use, the telescoping-tube assembly is reversibly and movably coupled to stationary platform 104 via a second coupling. The second coupling comprises male portion 124 and female portion 180. The male portion includes a spherical protuberance that depends from an end of the innermost tube 122. The female portion comprises receiver assembly 180, which is disposed on stationary platform 104. As used in this specification, including the appended claims, the term “movably coupled” means coupled in a way that permits relative movement between the items that are coupled by the coupling.

To couple telescoping-tube assembly 108 to stationary platform 104, lift mechanism 114, which is operatively coupled to the telescoping-tube assembly, raises distal end 110 of the telescoping-tube assembly. The angle of lift (i.e., the angle formed between telescoping-tube assembly 108 and deck 170 of vessel 102) is sufficient, when the tubes of the telescoping-tube assembly are extended, to couple the telescoping-tube assembly 108 to stationary platform 104. A typical angle-of-lift is about 60 degrees, but it could be more or less than this figure as a function of the relative heights of vessel 102 and platform 104. In the illustrative embodiment of system 100, lift mechanism 114 is a conventional hydraulic cylinder that is coupled to tube 118 of telescoping-tube assembly 108. In some other embodiments, the lift mechanism is a conventional pneumatic cylinder.

Lift mechanism must be coupled to deck 170 and telescoping-tube assembly 108 in a manner that assures that the telescoping-tube assembly is not over constrained. If over constrained, such as by the use of a rigid coupling between deck 170 and the lift mechanism, stresses would be induced in telescoping-tube assembly 108 during use, effectively defeating the stress-mitigating functionality of the first and second couplings. It is also important that the coupling between the lift mechanism, deck, and telescoping-tube assembly doesn't result in over constraining the telescoping-tube assembly. This could result in instability during lifting/lowering due to sideward tipping forces.

A coupling arrangement wherein a pin joint is used to couple the lift mechanism 114 to deck 170 and a conventional rod-end fitting (having end of travel stops) couples the lift mechanism to tube 118 is suitable for appropriately constraining the telescoping-tube assembly. The conventional rod end fitting has a ball and socket portion that accommodates a degree of misalignment and rotation in various planes.

Once tube 122 of telescoping-tube assembly 108 is coupled to stationary platform 104, there is no longer a need for the lifting force provided by lift mechanism 114. As a consequence, hydraulic (or pneumatic) pressure will be released after coupling, enabling telescoping-tube assembly 108 to “telescope,” thereby reducing induced stresses. In some embodiments, the pin joint (for coupling lift mechanism 114 to deck 170) is designed so that after the pressure to lift mechanism 114 is relieved, the pin joint accommodates motion in various planes. In some other embodiments, a lock-unlock mechanism is used at the lift mechanism/deck coupling. During lifting/lowering of telescoping-tube assembly 108, the mechanism is locked, which permits only pivoting (pitching) motion of lift mechanism 114. Otherwise, the lock-unlock mechanism is in an unlocked state, which permits motion in the pitch direction as well as movement in other rotational directions. In conjunction with this specification, it is within the capabilities of those skilled in the art to couple lift mechanism 114 to deck 170 and telescoping-telescoping tube assembly 108 in a manner that avoids over- or under-constraining the system.

In the illustrative embodiment, cables 202 and 204 connect tube 118 to vessel 102 and cables 206A and 206B connect tube 122 to stationary platform 104. The combination of lift mechanism 114 and cables 202, 204, 206A, 206B provide vertical and lateral positioning and stabilization for telescoping-tube assembly 108.

Cables 202, 204, 206A, 206B must be suitable to withstand the tension (resulting from the relative movement of vessel 102 and stationary platform 104) that is required to stabilize telescoping-tube assembly 108. The cables must also be corrosion resistant. Suitable materials for these cables include, without limitation, corrosion-resistant stainless steel, etc. In some embodiments, these cables are elastic/stretchable/resilient, such as a Bungee cable. It is within the capabilities of those skilled in the art to design or specify cables suitable for use in conjunction with the illustrative embodiment of the present invention.

It is to be understood that FIG. 2 provides a general indication of the orientation/direction of cables 202, 204, 206A, 206B. As appropriate, those skilled in the art will be capable of deciding whether it is necessary to use a larger number of cables, having the general orientations illustrated, for the purpose of stabilizing telescoping-tube assembly 108. In some embodiments, depending on the particular rotational degrees of freedom provided by the coupling arrangement for the deck 170/lift mechanism 114/telescoping-tube assembly 108 interface or provided by the first and/or second couplings, cables 202, 204, 206A, 206B can be omitted. This is a matter of selecting couplings for system 100 such that the system is appropriately constrained, which is within the capabilities of those skilled in the art. Specifically, appropriate selection of couplings will ensure that (1) the amount of stress induced in telescoping-tube assembly 108 during crew-transfers operations is desirably low; and (2) the telescoping-tube assembly is prevented from “rolling.”

This specification now proceeds with further details of the structure and operation of telescoping-tube assembly 108 and the first and second couplings.

Telescoping-tube assembly 108. As is depicted in FIG. 3 (via an end view from the perspective indicated at line 3-3 in FIG. 1C) and FIG. 4 (via a side cross-sectional view from the perspective indicated at line 4-4 in FIG. 2), telescoping tubes 118, 120, 122 include respective ladders 306, 308, 310. Each ladder comprises rung support 304 and a plurality of rungs 302. These ladders enable a crew member to traverse telescoping-tube assembly 108 and travel between support vessel 102 and stationary platform 104 in a safe manner while being protected from weather conditions.

With continuing reference to FIGS. 3 and 4, telescoping-tube assembly 108 includes a first mechanism for extending or retracting telescoping tubes 118, 120, 122. In the illustrative embodiment, that mechanism comprises a plurality of linear actuators 314, 316, 318, 320, 322, and 324.

In the illustrative embodiment, three linear actuators are disposed between any two tubes, arranged about 90 degrees apart. More specifically, linear actuators 314, 316, and 318 are disposed between the interior surface of tube 118 and the exterior surface of tube 120. And linear actuators 320, 322, and 324 are disposed between the interior surface of tube 120 and the exterior surface of tube 122.

The manner in which the linear actuators operate to extend/retract the tubes is described later in this specification in conjunction with FIGS. 10-13.

In the illustrative embodiment, the first mechanism (e.g., the linear actuators, etc.) serves a dual purpose. That is, in addition to being used to extend/retract the tubes, the first mechanism is also used to selectively “couple” or “lock” adjacent tubes to prevent relative movement between them. In some other embodiments, these two functions can be performed via separate mechanisms. This “locking” functionality and its significance are discussed in further detail later in this specification.

In the illustrative embodiment, the linear actuators are mechanically-coupled, rodless, pneumatic cylinders. Each such actuator includes a cylinder body and a mechanically-coupled piston yoke. For example, as is shown in FIG. 3, actuator 314 includes cylinder body 326 and mechanically-coupled piston yoke 330. Cylinder body 326 is mounted on inner surface 328 of telescoping tube 118. The movable portion of the rodless cylinder (i.e., piston yoke 330) is connected to adjacent tube 120.

Suitable mechanically-coupled, rodless, pneumatic cylinders include ULTRAN brand rodless cylinders, available from Bimba Manufacturing in Monee, Ill. Other types of actuators that are capable of providing the same functionality as the mechanically-coupled rodless pneumatic cylinders of the illustrative embodiment may suitably be used in alternative embodiments. Those skilled in the art are familiar with linear actuators and will be able to appropriately specify them for use in conjunction with the illustrative embodiment and alternative embodiments.

The first mechanism requires a source of power to extend/retract the tubes or selectively lock the tubes. In the illustrative embodiment, a plurality of electrically-operated control valves 416, 418, 420, and 422 and source 428 of pneumatic power (FIG. 4) serve this purpose. In particular, the first mechanism—linear actuators 316, 318, 320, 322, and 324—is driven by pressurized air that is selectively delivered via the control valves.

Telescoping-tube assembly 108 also includes a motion-sensing system that senses crew-member motion within telescoping tubes 118, 120, and 122. Referring now to FIG. 4, in the illustrative embodiment, the motion-sensing system includes a plurality of motion sensors 402, 404, 406, 408, 410, 412, two of which are disposed in each of telescoping tubes 118, 120, and 122. In the illustrative embodiment, the motion sensors are infra-red motion sensors. Other types of motion sensors (e.g., optical, etc.) may suitably be used. Those skilled in the art will know how to select and use other types of motion sensors for use in conjunction with the present invention.

As a crew member climbs through telescoping tubes 118, 120, and 122, motion sensors 402, 404, 406, 408, 410, and 412 sense, in sequence, the presence of the crew member. In this fashion, the location of the crew member can be resolved to a specific tube at any moment. Furthermore, the crew member's direction of travel through telescoping tubes 118, 120, 122 can be determined based on the sequential “tripping” of the sensors. That is, if sensor 406 indicates motion and then sensor 408 indicates motion, the crew member's direction of travel is towards the “right” in FIG. 4. If, on the other hand, sensor 406 indicates motion and then sensor 404 indicates motion, the crew member's direction of travel is towards the “left” in FIG. 4.

The motion-sensing system also includes control computer 414. In conjunction with suitable circuitry, etc., computer 414 receives signals from the motion sensors (i.e., indicative of a crew member's location and direction of motion) and generates one or more control signals based thereon. The control signal(s) are transmitted to one or more of electrically-operated control valves 416, 418, 420, and 422.

The control valves, which are fluidically coupled to source 428 of pneumatic power, are arranged to actuate linear actuators 314, 316, 318, 320, 322, 324. In the illustrative embodiment, each of the linear actuators is fluidically coupled to two of the electrically-operated control valves. For example, linear actuators 314, 316, 318 are each fluidically coupled to control valves 416 and 418. For simplicity and clarity, FIG. 4 depicts control valve 416 as being coupled only to actuator 314. The control signal(s) that are generated based on the output of the motion sensors are essentially a “lock/unlock” command for the linear actuators. It is within the capabilities of those skilled in the art to design or specify pneumatic connections and electrically-operated valves suitable for use in conjunction with the illustrative embodiment of the present invention.

Based on the input from the motion-sensing system and via operation of the linear actuators, the tube through which the crew member is moving and the adjacent telescoping tube in the crew member's direction of motion are coupled or locked together to prevent relative motion therebetween. More specifically, computer 414 generates signals that ultimately cause the appropriate control valves to actuate one or the other triad of linear actuators (i.e., linear actuators 314, 316, 318 or linear actuators 320, 322, 324) as required for coupling the particular two tubes together.

The crew member thus traverses adjacent telescoping tubes that are locked together, while relative motion is permitted between unlocked tube(s). For example, when a crew member travels from tube 118 to tube 120, tubes 118 and 120 are coupled/locked and tubes 120 and 122 are uncoupled/unlocked. Once the crew member reaches tube 120 and is determined to be moving toward tube 122, the tube 118/tube 120 coupling is released and tubes 120 and 122 are locked. The freedom of relative motion of the telescoping tubes (in the axial direction) that are not being currently traversed enables the telescoping-tube assembly 108 to accommodate relative motion between vessel 102 and the stationary platform 104. This selective coupling/uncoupling is described further later in this specification in conjunction with FIGS. 10 and 14. System 100 thereby provides safety to crew members and also accommodates the motion of support vessel 102 without inducing undue stresses in the system.

Three tubes are considered to be a minimum number of tubes for telescoping-tube assembly 108. Using a minimum of three tubes ensures that telescoping-tube assembly 108 can always accommodate relative motion between vessel 102 and stationary platform 104. That is, some portion of telescoping tube assembly 108 will be able to freely extend or retract. In conjunction with this specification, those skilled in the art will be capable of making and using alternative embodiments (not illustrated) in which telescoping-tube assembly 108 includes a larger number of tubes, each similar to the tubes that have been shown. The use of a greater number of tubes accommodates, for example, relatively greater distances between support vessel 102 and stationary platform 104.

First and Second Couplings. First coupling 112 includes a male portion that depends from telescoping-tube assembly 108 and a female portion that is disposed on support vessel 102. In the illustrative embodiment, these two portions effectively create a ball joint. With reference to FIG. 5, the male portion comprises spherical protuberance or ball 502 and stem 504. The stem extends from “lower” surface 506 of tube 118, near the end thereof. Ball 502 depends from stem 504.

The female portion comprises base support member 508, which is disposed on deck 170 of the first platform (e.g., the support vessel, etc.). Socket 510 is formed in base support member 508. Ball 502 is received by socket 510.

The ball joint formed by ball 502 and socket 510 accommodates roll, pitch and yaw motions of the first platform. This substantially reduces the stresses that would otherwise be induced in telescoping-tube assembly 108 when it is coupled to stationary platform 104. It is notable that, in the illustrative embodiment, first coupling 112 does not permit relative translational motion between telescoping tube assembly 108 and support vessel 102. This is because ball 502 is free to “spin” relatively unencumbered in socket 510, but it cannot “translate;” that is, it cannot move along a linear path. In the illustrative embodiment, linear movement, such as occurs when vessel 102 moves towards or away from stationary platform 104, is accommodated by the at least one free-to-move portion of telescoping-tube assembly 108.

In alternative embodiments, first coupling 112 is configured differently such that it can allow for translational motion, in addition to accommodating roll, pitch, and yaw motions. For example, in some of such alternative embodiments, a similar ball joint coupling is mounted on a “sled” that is free to slide back and forth, thereby accommodating relative translational movement between vessel 102 and stationary platform 104.

FIGS. 6-9 and the accompanying description provide detail of the second coupling, which movably and reversibly couples telescoping-tube assembly 108 to the second platform (e.g., stationary platform 104, etc.) FIG. 6 depicts male portion 124 of the second coupling coupled to the female portion 180. FIG. 7 depicts a top view of female portion 180 from the perspective indicated at line 7-7 in FIG. 6 (male portion 124 not depicted). FIG. 8 depicts a cross-sectional view through female portion 180 from the perspective indicated at line 8-8 in FIG. 6 (male portion 124 not depicted). FIG. 9 depicts a cross-sectional view through female portion 180 from the perspective indicated at line 9-9.

Male portion 124 of the second coupling includes ball 602 mounted on stem 604. The stem extends from the lower surface of tube 122 proximal to end 212 thereof. This arrangement is the same as ball 502 and stem 504 previously described. In the illustrative embodiment, female portion 180 of the second coupling is hereinafter referenced as receiver assembly 180. The receiver assembly includes a socket (see FIG. 8, socket 810), which is formed in base 612 that is mounted on deck 614 of stationary platform 104.

During operation, the linear actuators and lift mechanism 114 move end 212 of tube 122 to position ball 602 to drop into socket 810. Remotely-controlled socket cover 616 (see FIGS. 6 and 7) slides over ball 602, thereby effectively locking end 212 of telescoping tube 122 to deck 614 of stationary platform 104. As depicted in FIG. 9, socket cover 616 includes dovetail guide 920, which is slideably mounted in guide way 922 formed in base 612. Motion of socket cover 616 in the directions indicated by arrow 636 in FIG. 6 is controlled by linear actuator 628 driven by electric motor 630. The motor is controlled by wireless remote control unit 632 and brake 634.

Slot 702 (FIG. 7) in socket cover 616 is suitably dimensioned to prevent the ball from dislodging from socket 810 while accommodating movement of stem 604. Such movement, which includes movement in the roll, pitch, and yaw directions, will occur as vessel 102 (and telescoping-tube assembly 108 situated thereon) moves in response to wave motion.

As previously discussed, in some embodiments, to prevent telescoping-tube assembly 108 from “rolling,” cables 206A and 206B are used (see FIG. 2). In this fashion, the three degrees of freedom that would otherwise be provided by the second coupling is reduced to only two degrees of freedom of movement (i.e., pitch and yaw). Like first coupling 112, the ability to accommodate this movement substantially reduces the stresses that would otherwise be induced in system 100 when telescoping-tube assembly 108 couples a wave-tossed vessel to a stationary platform. There are many ways to modify the second coupling so that it provides two, rather than three, rotational degrees of freedom. For example, a pin (not depicted) can be inserted through ball 602. Socket cover 616 can be suitably configured so that once the socket cover engages ball 602, the pin prevents the telescoping-tube assembly from rolling. Alternatively, the second coupling can be modified so that stem 604 extends into slot 702 of the socket cover. This would likewise prevent telescoping-tube assembly 108 from rolling, while still accommodating movement in the pitch and yaw directions.

In the illustrative embodiment, the second coupling, like first coupling 112, cannot accommodate translational movement. In some alternative embodiments, the second coupling is configured to accommodate translational movement, such as discussed above in conjunction with the first coupling.

Linear Actuators. FIG. 10 provides additional detail of the linear actuators previously discussed (i.e., linear actuators 314, 316, 318, 320, 322, 324). As depicted in FIG. 10, rodless cylinder type actuator 1002 includes cylinder body 1050 with a central bore 1052 and a piston 1056 which slides in bore 1052. Piston 1056 divides bore 1052 into first chamber 1058 and second chamber 1060. Yoke 1054 is rigidly coupled to the exterior of tube 120 and is mechanically coupled to piston 1056. In some embodiments, the yoke and piston are a unitary element; in some other embodiments, the yoke and piston are distinct elements that are mechanically coupled to one another (e.g., attached to one another, etc.) Sealing of first and second chambers 1058, 1060 is accomplished via an elongated elastomeric seal 1062 that flexes to accommodate motion of yolk 1054/piston 1056 and a flexible steel backing strap or band 1064 that runs through slot 1066 in yoke 1054.

Extension/Retraction Functionality. Application of pneumatic pressure to first chamber 1058 via port 1070 drives piston 1056 and yoke 1054 toward the “right” to second chamber 1060. This, in turn, causes tube 120 to move to the “right.” If telescoping-tube apparatus 108 is oriented as depicted in FIG. 4, such rightward movement would cause tube 120 to deploy; that is, to “telescope” out of tube 118. Application of pneumatic pressure to second chamber 1060 via port 1072 drives piston 1056 and yoke member 1054 toward first chamber 1058. This, in turn, causes tube 120 to move to the “left.” If telescoping-tube apparatus 108 is oriented as depicted in FIG. 4, such leftward movement would cause tube 120 to retract into tube 118.

Coupling/Locking Functionality. Closing the control valves that supply pressure to first and second chambers 1058, 1060 locks piston 1056 and yolk 1054 in place and locks adjacent tubes (e.g., tubes 118 and 120) to one another. In this state, there can be no relative movement between locked tubes. Note that this does not mean that locked tubes do not move; it means that there is no relative movement between these tubes. For example, if tubes 120 and 122 are locked, which means that tube 118 is not locked to tube 120, it is possible for tubes 120 and 122 to collectively move toward 118 when vessel 102 (due to wave motion) moves closer to platform 104. But what is important is to prevent relative motion between the locked tubes so that a crew member can safely transit from one (locked) tube to the next.

Floating Functionality. Releasing the pressure in chamber 1052 allows piston 1056 and yoke 1054 to “float.” In such case, relative motion between tube 118 and tube 120 is permitted. Since, in the illustrative embodiment, tube 118 is the outermost tube and is not movable, tube 120 will move to accommodate relative movement between the first platform (e.g., vessel 102) and the second platform (e.g., stationary platform 104) towards or away from one another by extending or retracting.

The floating functionality is depicted via the representations shown in FIG. 14. For clarity, only telescoping-tube assembly 108 is depicted in these Figures. The “upper” representation in FIG. 14 depicts the telescoping-tube assembly fully deployed. Tubes 120 and 122 are assumed to be locked and relative motion is permitted between tubes 118 and 120. Tube 118 is assumed to be coupled to a vessel (not shown) and tube 122 is reversibly coupled to a stationary platform (not shown).

In the lower representation of FIG. 14, the vessel on which telescoping-tube assembly 108 resides has moved closer to the stationary platform. Since relative motion is permitted between tubes 118 and 120, as the vessel moves closer to the platform, tube 120 “retracts” into tube 118. Actually, movement is to the “right” in FIG. 14. That is, tube 120 does not move; rather, the vessel and tube 118 move to the right by a distance “D.” This has the effect of shortening the telescoping-tube assembly by the length “L.” In this fashion, the length of telescoping-tube assembly 108 is “automatically” altered to accommodate a change in the relative position of the first platform and the second platform.

In alternative embodiments of the invention, other cylinders which may be utilized include: magnetically coupled rodless pneumatic, magnetically coupled rodless hydraulic cylinders, cylinders using magneto-rheological (MR) fluid, as well as electro-mechanical actuators.

It is within the capabilities of those skilled in the art to design or specify pneumatic, hydraulic connections and electrical connections and electrically operated valves suitable for use in conjunction with the illustrative embodiment of the present invention and the alternative embodiments of the present invention. While rodless type cylinders as described above provide advantages in reduction of size relative to conventional rod type pneumatic or hydraulic cylinders, it should be understood that conventional pneumatic and hydraulic actuator cylinders using magneto-rheological (MR) fluid maybe utilized as well as electro-mechanical actuators may be utilized.

As depicted in FIG. 11, in magneto-rheological (MR) fluid actuators, the hydraulic fluid utilized in a conventional hydraulic cylinder is replaced by a magneto-rheological (MR) fluid and an electromagnet 1104 is mounted on cylinder 1102. Magneto-rheological (MR) fluids are oil-based suspensions of microscopic ferrous particles. When a magnetic field is applied across the fluid, the particles align and resist flow, and quickly become transformed from a fluid to a near solid. The speed of the transformation from a fluid to a near solid is on the order of milliseconds. One source for MR fluids is Lord Corporation of Cary, N.C. The locking capability of the MR fluid actuator provides an alternative to the valve locking system utilized with conventional pneumatic and hydraulic actuators previously described. The elimination of the valve system provides a reduction in the cost and complexity of the system.

As is depicted in FIG. 12, a magnetically coupled rodless cylinder or linear actuator 1200 is generally similar to rodless cylinder 1002 previously described with the exception that elongated elastomeric seal 1062 and flexible steel band 1064 have been eliminated and piston 1202 is magnetically coupled to piston yoke member 1204. Actuator 1200 includes cylinder body 1206 with a central bore 1208 and piston 1202 which slides in bore 1208. Piston 1202 divides bore 1208 into a first chamber 1210 and a second chamber 1212. Piston 1202 and piston yoke member 1204 each include a strong magnet 1214, 1216 and piston yoke member 1204 moves with piston 1202. Sealing of first and second chambers 1210 and 1212 is accomplished via conventional seals which have not been illustrated. Application of pneumatic pressure or hydraulic pressure to first chamber 1210 drives piston 1202 and piston yoke member 1204 toward chamber 1212. Similarly, application of pressure to second chamber 1212 drives piston 1202 and the piston yoke member 1204 toward the first chamber 1210. Closing valves leading to first and second chambers 1210, 1212 locks piston 1202 and piston yolk member 1204 in place and locks adjacent tubes for example tubes 118, 120. Additional details of construction of this unit are known in the art and have therefore not been further described.

As is shown in FIG. 13, a conventional electro-mechanical ball screw actuator 1300 may be used to connect and drive the relative positions of tubes 118, 120. Electromechanical actuator 1300 includes a base 1302 connected to surface 1304 of, for example, tube 118. Base 1302 supports electric motor 1306 connected to gearbox 1308 which drives ball screw 1310. End 1312 of ball screw 1310 is connected to, for example tube, 120. Electric motor 1306 is connected to motor controller 1314 and brake 1316. Motor controller 1314 is connected to a source of electrical power via conventional electrical connections that have not been illustrated. Additional details of construction of this unit are known in the art and have therefore not been further described.

Linear actuators 314, 316, 318, 320, 322, 324 may include conventional internally-mounted position sensors, not illustrated, for sensing end-of-linear-actuator travel. The end-of-travel sensors provide an electrical signal responsive to full extension and full retraction of telescoping-tube assembly 108. As is depicted in FIG. 1 when fully retracted, telescope tube assembly 108 may be stowed on the vessel deck in an efficient manner.

FIG. 15 depicts a method 1500 for transferring crew members from a first platform, such as vessel floating in water, to a second platform, which in some embodiments is stationary, such as an oil rig platform. The method includes the following operations:

-   -   Op. 1502: Extending, from a first platform to a second platform,         a plurality of telescoping tubes.     -   Op. 1504: Temporarily coupling, to the second platform, an end         of a distal-most tube of the telescoping tubes.     -   Op. 1506: Sensing a presence of a user moving within the         telescoping tubes.     -   Op. 1508: Determining a direction of travel of the user.     -   Op. 1510: Locking/coupling both the telescoping tube in which         the user is present (at the time of sensing) and an adjacent         telescoping tube in the direction in which the user is         traveling.

Operations 1502 through 1510 have been previously discussed in the context of the description of crew transfer system 100. Additional operations, some optional, will also be conducted. For example, in some embodiments, before the telescoping tubes (e.g., tubes 118, 120, and 122, etc.) are extended, a cable (see, e.g., FIGS. 1A-1C, 2: cable 106) is used to couple the first and second platforms to each other. Furthermore, since the first platform will often be lower than the second platform, the anterior end of the telescoping tubes is raised using a mechanism (see, e.g., FIG. 1B, lift mechanism 114).

Regarding operation 1510 and as previously discussed, tubes that are not currently being traversed are free to move relative to each other and thereby accommodate movement between the first platform and the second platform. Consider, for example, a user entering a telescoping-tube assembly having three tubes. As the user first enters the assembly (from posterior end 109), the first tube and second tube are locked. As the user exits the first tube and enters the second tube, the first tube/second tube “lock” is released and the second tube and third tube are then locked. To the extent that a telescoping tube assembly includes more than three tubes, all tubes other than the tube in which the user presently resides and the adjacent tube in the user's direction of travel are free to float.

It is to be understood that the above-described embodiments are merely illustrative of the present invention and that many variations of the above-described embodiments can be devised by those skilled in the art without departing from the scope of the invention. It is therefore intended that such variations be included within the scope of the following claims and their equivalents. 

1. A crew-transfer system comprising: a telescoping-tube assembly comprising: (a) at least three tubes; and (b) a first mechanism that selectively locks two adjacent tubes of the at least three tubes, wherein the tubes are selected for locking based on: (i) a location of a user within the telescoping-tube assembly; and (ii) a direction of travel of the user therethrough, wherein the locked tubes include the tube in which the user resides and the tube to which the user is next heading; and a first coupling that movably couples a posterior end of the telescoping-tube assembly to a first platform that, in use, is subjected to forces that cause the first platform to move; and a second coupling that movably and reversibly couples an anterior end of the telescoping-tube assembly to a second platform.
 2. The system of claim 1 and further wherein the first mechanism also extends and retracts the at least three tubes.
 3. The system of claim 1 wherein the first mechanism comprises a plurality of linear actuators.
 4. The system of claim 3 wherein the linear actuators comprise one of either mechanically-coupled, rodless cylinders or magnetically-coupled rodless cylinders.
 5. The system of claim 3 wherein the at least three tubes include an outermost tube, an intermediate tube, and an innermost tube, and further wherein: a first group of the plurality of linear actuators are disposed between an inside surface of the outermost tube and an outside surface of the intermediate tube; and a second group of the plurality linear actuators are disposed between an inside surface of the intermediate tube and an outside surface of the innermost tube.
 6. The system of claim 1 wherein the first coupling provides at least three degrees of relative movement between the first platform and the telescoping-tube assembly.
 7. The system of claim 6 wherein the first coupling comprises a ball and socket joint.
 8. The system of claim 1 wherein, when coupled to second platform, the anterior end of the telescoping tube assembly is movable in a pitch direction and a yaw direction, but not in a roll direction, to accommodate relative movement between the telescoping-tube assembly and the second platform.
 9. The system of claim 8 wherein the second coupling comprises a ball and socket joint.
 10. The system of claim 1 wherein the telescoping-tube assembly further comprises a plurality of ladders within the tubes.
 11. The system of claim 1 and further comprising a motion-sensing system for sensing the location and direction of travel of the user within the tubes.
 12. The system of claim 11 wherein the motion-sensing system comprises a plurality of motion sensors, wherein the motion sensors are disposed in the tubes.
 13. The system of claim 11 wherein the first mechanism is controlled based on output from the motion-sensing system.
 14. The system of claim 1 and further comprising a second mechanism for raising the anterior end of the telescoping-tube assembly.
 15. A crew-transfer system comprising: a telescoping-tube assembly comprising: (a) at least three tubes that allow ingress and egress for a user; (b) a motion-sensing system for sensing the presence and direction of movement of the user through the tubes; and (c) a first mechanism for extending and retracting the at least three tubes; a first coupling that couples a posterior end of the telescoping-tube assembly to a first platform that, in use, is subjected to forces that cause the first platform to move in at least three different directions, wherein the first coupling is structured to accommodate the movement of the first platform by providing a least three degrees of freedom of movement between the telescoping-tube assembly and the first platform; and a second coupling that reversibly couples an anterior end of the telescoping-tube assembly to a second platform.
 16. The system of claim 15 wherein the telescoping-tube assembly further comprises a plurality of ladders within the tubes.
 17. The system of claim 15 wherein the motion-sensing system comprises a plurality of motion sensors, wherein the motion sensors are disposed in the tubes.
 18. The system of claim 15 wherein the three degrees of freedom of movement provided by the first coupling accommodates movement of the first platform in the roll, pitch and yaw directions.
 19. The system of claim 15 wherein the first mechanism also selectively locks two adjacent tubes of the at least three tubes, wherein the tubes are selected for locking based on: (a) a location of a user within the telescoping-tube assembly; and (b) the direction of movement of the user through the telescoping tube assembly, wherein the locked tubes include the tube in which the user is present at the time of sensing and the tube to which the user is next heading.
 20. The system of claim 19 wherein selective locking, as effected by the first mechanism, is controlled based on output from the motion-sensing system.
 21. The system of claim 15 further comprising a second mechanism, wherein the second mechanism selectively locks two adjacent tubes of the at least three tubes, wherein the tubes are selected for locking based on: (a) a location of a user within the telescoping-tube assembly; and (b) the direction of movement of the user through the telescoping tube assembly, wherein the locked tubes include the tube in which the user resides at the time of sensing and the tube to which the user is next heading.
 22. The system of claim 15 wherein the first mechanism comprises linear actuators that include one of either mechanically-coupled or magnetically-coupled rodless cylinders.
 23. The system of claim 15 and further comprising a second mechanism for raising the anterior end of the telescoping-tube assembly.
 24. A crew-transfer system comprising: a telescoping-tube assembly, the telescoping-tube assembly comprising: (A) at least three tubes that allow ingress and egress for a user; (B) a motion-sensing system for sensing the presence of the user and a direction of movement of the user through the tubes; and (C) one or more mechanisms that: (i) extend and retract the at least three tubes; (ii) selectively lock two adjacent tubes of the at least three tubes based on: (a) a location of a user within the telescoping-tube assembly; and (b) a direction of travel of the user therethrough, wherein the locked tubes include the tube in which the user resides at the time of sensing and the tube to which the user is next heading; a first coupling that couples a posterior end of the telescoping-tube assembly to a first platform; and a second coupling that reversibly couples an anterior end of the telescoping-tube assembly to a second platform.
 25. The system of claim 24 wherein the first coupling movably couples the posterior end of the telescoping-tube assembly to a first platform.
 26. The system of claim 24 wherein the second coupling movably couples the anterior end of the telescoping-tube assembly to the second platform.
 27. A crew-transfer system that couples to a first platform and reversibly couples to a second platform, wherein the crew-transfer system comprises: a telescoping-tube assembly, the telescoping-tube assembly comprising: (A) a first tube, second tube, and third tube that are suitably dimensioned to permit passage through by a human user; (B) a motion-sensing system for sensing the presence of the user and a direction of movement of the user through the tubes; and (C) a plurality of linear actuators selected from the group consisting of mechanically-coupled rodless cylinders or magnetically-coupled rodless cylinders, wherein the linear actuators are disposed between: (i) an inner surface of the first tube and an outer surface of the second tube; and (ii) an inner surface of the second tube and an outer surface of the third tube.
 28. The system of claim 27 and further wherein the linear actuators are arranged to extend and retract the second tube and third tube.
 29. The system of claim 27 and further wherein the linear actuators are arranged to selectively lock the first tube and the second tube or the second tube and third tube based on: (A) a location of a user within the telescoping-tube assembly at the time of sensing; and (B) a direction of travel of the user therethrough.
 30. The system of claim 29 and further wherein the linear actuators are arranged so that when a user transits from the first tube to the second tube: (A) the linear actuators decouple the first tube from the second tube to enable relative movement therebetween; and (B) the linear actuators couple the second tube and the third tube to prevent relative movement therebetween.
 31. A method comprising: extending, from a first platform to a second platform, a plurality of telescoping tubes; temporarily coupling, to the second platform, an end of a distal-most tube of the telescoping tubes; sensing a presence of a user moving within the telescoping tubes; determining a direction of travel of the user; and locking both the telescoping tube in which the user resides at the time of sensing and an adjacent telescoping tube in the direction in which the user is traveling. 